This invention relates to methods of manufacturing insulated glass units (IGUs). More particularly, it refers to methods of forming sealed IGUs by adhesively coating a pair of glass substrates with a thin multi-layered film, the film's outer layer having a metallized coating applied by vacuum deposition or sputter-deposition.
It is known that energy is controlled at a window by the reflection, transmission and absorption of solar radiation by the glazing type and emissivity of the glazing. An IGU contributes to the heat gain or loss of the window by three mechanisms: conduction of heat, convection whereby air currents within the IGU act as the transfer agent for heat, and radiation or reradiation of the heat absorbed. When solar radiation strikes an IGU energy is absorbed and either conducted or reradiated. The ability to reradiate is called emissivity. When a spectrally selective, vacuum deposited, metal or metallic coating is incorporated into the surface within an IGU, it assists with energy release by absorbing the IR portion of the solar spectrum and reradiating the absorbed energy to the surrounding atmosphere in the direction of the surface of the coating and the atmosphere interface. If the spectrally selective coating is encapsulated within a film or system and the coating itself is not exposed to the environment, the majority of the ability to reradiate energy is lost as conduction becomes the major pathway for the absorbed energy. It is important for a spectrally selective coating to be exposed to an atmosphere in order to reduce the energy transfer by reradiation of the absorbed energy. Standard laminated glass where two pieces of glass are adhered together by a plastic do not incorporate spectrally selective, vacuum deposited, metal or metallic coatings within the laminate for this reason.
The ability to incorporate a spectrally selective, vacuum deposited, metal or metallic coating within an IGU utilizing a film composite having an emitting coating on the inner surface or surfaces of the IGU provides enhanced absorbed heat dissipation capability as it takes advantage of the filtering out of IR light, absorbs most of the UV portion of the spectrum, allows for neutral colored visible light to be transmitted, and takes advantage of the emissivity of the coating to reradiate absorbed light. This provides for a better insulation value for the IGU portion of the window and enhanced safety performance because of the film laminate adhered to the inner surface of the glass.
It is known that the reactivity of spectrally selective coatings consisting of multi-layers of vacuum deposited or sputter-deposited metals or metallic compounds can corrode depending on the chemical composition when exposed to moisture or other chemicals. When this happens the corrosion products are aesthetically displeasing and the solar radiation controlling performance of the coatings is lost. A manufacturing method is needed to avoid this corrosion problem.